Something bad i wrote on my birthday.. will improve later

A smiling face, a birthday cake
You wouldn't guess that smile is fake
She struggles to eat what her sister struggled to make
As she celebrates the life she wanted to take

The food, to her, looks unclean
And nothing is the way it seems
She likes to pretend it's all a dream
She's terrified to think she's fifteen

Has it really been fifteen years?
Has it really been so many calories and tears?
Somehow she's survived all of her fears
But bit by bit she disappears